If i recall correctly, the Americans durring the American Revolution were a bunch of rag-tag farmers and business men, but their resolve allowed them to defeat the worlds most powerful military force.
Wrong paradigm. The Royal Navy won the Revolutionary War. You cannot extemporize a navy. The NTF's officer corps and senior NCOs are most likely defectors. Rank and file crewmen would be new recruits. Defecting to the NTF early would have been a fast route to promotion as they spread out their experienced people to cover reactivated ships from somebody's boneyards since it's unlikely they could stand off the GTVA with the production of only three colonies to the GTVA's 20+.
It's possible that it would take hours to get all the ship's onboard fighters readied and aloft. I think flight ops are generally kept at a sustainable tempo and it's probably hard to instantly ramp up to maximum panic mode.
I doubt it has anything to do taking hours because, frankly, that's dumb design. If you have a power-projection asset that isn't able to project power, it's worthless. We also know it's possibly to rapidly conduct automated arming operations for example, so there's evidence that things are exactly the opposite.
I think it has to do with damage-control issues. A detonation in a hanger is just begging to cause a ship serious issues. As long as the destroyer is not directly engaged they will conduct high-tempo flight operations as much as they want, launching fighters directly from the hanger deck while they keep a ready group situated on the flight deck. In the event enemy craft approach the destroyer then the link between hanger and flight deck is immediately sealed with heavy armor to protect the ship and the ship fights it out with its ready group and whatever fighters it can recall from ongoing missions.